European Union Recovery and Resilience Facility projects

To this end, the transmission capacity of existing overhead lines in the 110–330 kV network was increased, and the 110 kV network was more closely integrated with the 330 kV transmission network in order to reduce the impact of cross-border power flows through the local 110 kV electricity network, which can constrain opportunities for local generators to connect additional capacity.

This also required strengthening the connection between Western and Eastern Estonia within the 330 kV network. To this end, the 330 kV Kiisa–Paide overhead line L357 was fully reconstructed to increase transmission capacity, and part of the 110 kV Paide–Rapla overhead line L187 was relocated onto shared towers. The 330 kV Viru–Paide overhead line L356 was dismantled from the Viru substation to the new Mustvee substation, while the existing overhead line between the Mustvee and Paide substations was reconstructed (reducing the line corridor by approximately 85 km). As a result, the former Viru–Paide line was replaced by the Mustvee–Paide line. The construction of the Mustvee–Paide line made use of a shared-line configuration with the 110 kV Mustvee–Kantküla line.

In addition, a new 330/110 kV substation was built in Lihula. The new substation shortens the lengths of 110 kV lines in the western region, thereby reducing the adverse effects and losses caused by voltage drops, increasing security of supply, and improving the integration of the 330 kV and 110 kV networks. The new 330 kV substation also reduces the impact of north–south transit power flows through the 110 kV network in Western Estonia. Furthermore, the new Lihula substation makes it possible to establish separation points that can completely eliminate transit flows, particularly on weaker lines.

To this end, the security of electricity supply for Saaremaa and Muhu was improved by reconstructing the lines supplying the islands from the mainland between the Lihula substation and the Rõuste and Virtsu substations. In addition, a new 110 kV overhead line section was constructed from Rõuste to the L170 Lihula–Virtsu line, creating a three-terminal 110 kV overhead line connecting Lihula, Rõuste, and Virtsu.

A parallel Võiküla–Orissaare line was also constructed on separate towers on Muhu, as the lines supplying Saaremaa, Hiiumaa, and part of Muhu had previously been carried on shared towers. Consequently, the failure of a single tower could have resulted in a complete loss of the islands’ connection to the mainland power system. To further improve security of supply in the Sikassaare area, the lines connecting to the Sikassaare substation were also constructed on separate towers.

To reduce environmental impacts and increase resilience to weather conditions, it was necessary to cable the overhead line section running over the Väike Strait Dam. The overhead line previously crossing the causeway passed through a bird migration corridor and, because it traversed a marine environment, was exposed to a higher-than-normal risk of ice accretion and wind loading.

In addition, to increase transmission capacity in Western Estonia and the island region, the clearances of existing 110 kV lines were upgraded by increasing the distance between the conductors and the ground.

• Reconstruction of overhead line L356 Mustvee–Paide

• Reconstruction of overhead line L357 Kiisa–Paide

• Splitting the line L175 Leisi–Sikassaare from line L176 Sikassaare–Valjala onto separate pylons

• Clearance increase on line L174 Rõuste–Leisi

• Conductor replacement and clearance increase on line L177 Orissaare–Valjala

• Clearance increase on line L176 Sikassaare–Valjala

• Clearance increase on branch line L175A Valjala

• Clearance increase on line L175 Sikassaare–Leisi

• Construction of 110 kV overhead line L036 Rõuste–Virtsu

• Construction of 110 kV overhead line L170 Lihula–Virtsu

• Reconstruction of line L017 Kiisa–Rummu

• Clearance increase on line L185 Kiisa–Kohila

• Clearance increase on line L186 Kohila–Rapla

• Construction of parallel line L173 Võiküla–Orissaare

• Construction of Lihula 330/110 kV substation

• Extension works at Orissaare 110 kV substation

• Construction of 110 kV cable line section L174 Rõuste–Leisi in Väike Strait

The investments made under the program are illustrated in the diagrams:

Figure 1. Investments Enabling Increased Distributed and Renewable Electricity Volumes in Western Estonia and the Islands

Figure 2. Investments Enabling Increased Distributed and Renewable Electricity Volumes in Vestern Estonia and the Islands – Mainland Section

Figure 3. Investments enabling increased distributed generation and renewable energy capacity in Western Estonia and the islands